This is a kind of debugging feature for atomic reference counter.The reference counters are widely used in perf tools but not welldebugged. It sometimes causes memory leaks but no one has noticedthe issue, since it is hard to debug such un-reclaimed objects.

This refcnt interface provides fully backtrace debug feature toanalyze such issue. User just replace atomic_t ops with refcntAPIs and add refcnt__exit() where the object is released.